The purpose is to isolate and characterize enzymes involved in the biosynthesis of lactose which are a UDP glucose Pyrophosphorylase, UDP-galactose-4-Epimerase, and Lactose Synthetase. Lactose synthetase requires two proteins for activity, a galactosyltransferase and alpha-lactalbumin. This protein-protein interaction is studied by kinetics and chemical modification techniques. The galactosyltransferase is also involved in the biosynthesis of glycoproteins.